246 GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION. 



short range in time of the different species and genera. It is in- 

 deed true, as far as the genera are concerned, that the very limited 

 number of areas of deep-sea deposits may satisfactorily explain the 

 absence, as fossils, of the greater number of the modern genera, but 

 this circumstance will scarcely account for the distinctness of the 

 species. None of the species of the English Tertiaries, from the 

 Crag to the Eocene, are living forms, and the same appears to 

 be the case with the species from the German and Italian Oligo- 

 cene. In his enumeration of the species from the Miocene deposits 

 of Austria, Professor Reuss admits but a single recent form, Cary- 

 ophyllia clavus. 91 Not a single one of the species of the West India 

 Miocene deep-sea Madreporaria is, according to Duncan, a member of 

 the recent coral fauna, and yet just here a certain stability of physi- 

 cal conditions would have been supposed to ensure a steady per- 

 petuation of the species. Similarly, if we except two or three spe- 

 cies no longer found in the region, the extensively distributed 

 Dyltocyathus Italicus, and Flabellum Candeanum, from the China 

 seas, and F. distinctum, from the Red and Japanese seas, all of the 

 Australian Tertiary (Miocene or Pliocene) Madreporaria are extinct, 

 and, what is very remarkable, only a very insignificant fraction of 

 the living local genera is represented specifically in the Tertiary 

 deposits of that region. Conocyathus sulcatus, a species from the 

 Oligocene beds of the Maintz basin, is recognised by Duncan as a 

 member of the recent Australian fauna." 2 



The restricted specific longevity here indicated is certainly in 

 marked contrast to what obtains among the Mollusca, where, as is 

 well known, the recent forms constitute a no inconsiderable per- 

 centage of the Miocene fauna, and are not even wholly absent from 

 the fauna of the Eocene series.* And yet the Mollusca would seem 

 to be much more dependent for their existence upon special physi- 

 cal conditions of their surroundings than are the corals. The sur- 

 prising persistence of the Foraminifera is, by way of contrast, not a 

 little remarkable. 



The limited range in time of the species and genera of deep-sea 



* The late Mr. Gwyn Jeffreys has recently attempted to show that none of 

 the Eocene molluscan species are identical with living forms. Whether this be 

 so or not, there can be no question as to the existence of a limited number of 

 representative types, which unmistakably bind together the past and present 

 faunas, and in a manner which we do not find among the corals. 



